Dispenser for hygroscopic materials



R. w. wARlNG 2,568,526

DISPENSER FOR HYGROSCOPIC MATERIALS Sept. 18, 1951 Filed May l, 1947 s1 gf I 43 ml f''z f "f-"f g ENVENTZER "'ML wwf-maxim Patented Sept. 18, 1951 UNITED STATES PATENT OFFICE DISPENSER FOR HYGROSCOPIC MATERIALS Robert W. Waring, Fairfield, Conn.

Application May 1, 1947, Serial No. 745,173

3 Claims.

This invention is directed to a dispenser for salt, sugar or other granulated or pulverized substance having an ainity for moisture. For illustrative purposes, the following description will be directed to a salt shaker, it being understood, however, that my dispenser is equally well adapted for use with other substances that have a tendency to cake or clog by reason of their deliquescent or hygroscopic properties.

The proclivity of salt to cake and clog in the conventional salt shaker or cellar is, of course, well known, and various expedients have been resorted to in an effort to obviate this annoying occurrence. One type of shaker (see U. S. patent to Nagel 2,160,602) that has been commercially oiered is characterized by a perfor-ated dispensing head constructed of a material having an aflinity for moisture apparently intended to prevent caking adjacent the dispensing perforations. On the basis of tests described hereinbelow, however, I found but little improvement in the caking proclivity of the salt when stored in this type of shaker,

Another type of shaker (see U. S. patent to Beebe 1,937,505) which has been proposed includes a dispensing head having an elongated tube connected thereto, and adapted to extend nearly to the bottom of the shaker. While this type of shaker affords greater protection against the entrance of moisture, it is only by prolonged and vigorous shaking that it is possible to dispense a satisfactory amount of salt.

It is accordingly among the objects of my invention to provide a shaker for salt or other deliquescent materials that overcomes the aforementioned disadvantages in a thoroughly simple and practical manner. Other objects will be in part pointed out and in part apparent.

I have found that the transmission of water vapor from a region of relatively high vapor pressure to one of relatively low vapor pressure is inhibited by means of an elongated connection between the two regions. In making tests with hygroscopic materials, I have found that if the high vapor pressure region and the region containing the hygroscopic material are connected by a tube, the length of which is four or five times or more greater than the diameter of the tube, little or no water vapor is transmitted from the high vapor pressure region to the low. The rate of transmission apparently increases progressively as the length to diameter ratio of the connecting tube is decreased tow-ard unity or below. For instance, if the total difference in vapor pressure is considered to be 100, and the length to diameter ratio of the connecting tube is 1, the total difference in vapor pressure of 100 will be applied across this length, resulting in fairly rapid water vapor transmission. If, on the other hand, the length to diameter ratio of the connecting tube is 10, the vapor pressure differential per unit of length becomes 10, and the rate of transmission is relatively lower.

In employing this principle in the tests outlined hereinbelow, the rate of moisture vapor transmission appears to decrease progressively from very high rates, where length to diameter ratios of 1 or less are employed, until ratios of 5 or more are reached, where the water vapor transmission is effectively reduced to negligible amounts.

In accordance with one form of my invention, I take advantage of this phenomenon by providing the container of the material, e. g. salt, with a detachable dispensing head constructed of material having a relatively low ailinity for moisture relatively to the powdered material within the container, and which is preferably, although not necessarily substantially chemically inert. This dispensing head has sufcient axial length that the dispensing holes extending through the head have a length of the order of 4 or more times their diameter. Thus, where the dispenser or shaker is not subject to an atmospheric condition of extremely high humidity, the length to diameter ratio of the dispensing holes may be of a relatively low order of about 4 to 1, whereas better results may be obtained under conditions of very high humidity where the length to diameter ratios is considerably in excess of 4 to 1.

Referring now to the drawing, wherein there is illustrated one embodiment of my invention,

Figure 1 is a top plan view of a salt shaker having a dispensing head constructed in accordance with the invention;

Figure 2 is a 'fragmentary sectional elevation taken along the line 2 2 of Figure l Figure 3 is a plot of the vapor transmission rate against length to diameter ratios of the holes in the dispensing head;

Figure 4 is a sectional elevation of a modified form of the dispensing head;

Figure 5 is a horizontal section taken along the line 5-5 of Figure 4;

Figure 6 is a sectional elevation of still another form of my dispensing head; andt Figure 7 is a bottom plan view of the head shown in Figure 6.

Referring iirst to Figure 2, the dispenser includes a container 3, which may be oi any desirable form, and which may include a neck 4, provided with external attaching formations such as threads 5,' so as to detachably receive a dispensing head generally indicated at 6. While this dispensing head 6 may be constructed of any material which is not deliquescent or hygroscopic, and which possesses the characteristic of low moisture absorption relative to the substance bethe addition of a plasticizer which, under certain circumstances, might well leach out and adulterate the contents of the dispenser. The container 3, as noted above, may be constructed of glass, china or any other suitable or convenient material.

Dispensing head 6 is so formed or molded as to have an annular recess or groove 'l in one side Ta of which attaching threads lb are formed' for connection to neck threads 5. Preferably the top of the annular groove l is provided with one or more annular ridgesy 8 adapted to bear against the top of neck l when the head 6 is screwed thereon and be slightly compressed to eiect a complete seal between the container neck and therdis-pensing head', thus to preclude any possibility vof moisture-laden air entering the container and hence avoid interlocking with one another, as might well otherwise occur, particularly where the particles are crystalline in nature.

The tests hereinbefore referred to were conducted in sealed vglass chambers.v In the center of each chamber Was placed a glass containing Water, with a piece of blotting paper extending up the side of the glass in order to increase the amount of moisture in contact with the air. The dispensers under test Were placed around the glass water reservoir in approximately a six inch circle. The following procedure was used: the glass, blotter and water were weighed at the beginning of each test. Each dispenser assembly was carefully dried under an infra red lamp and charged with salt which had also been given an infra red dryingA period. After charging the salt and screwing on the top, each dispenser was weighed and placed in position in the test chamber.- The chamber was then sealed and left in this condition until the end of the test. The amount of salt charged into the dispensers varied between ten and twenty-five grams, depending upon the shape of the dispenser. Thel duration of each test was120 hours or more, during'which period the above-mentioned conditions were maintained'.

The results of these tests are set forth in the following summary:

Summary of dispenser testsY Container Construction' Standard salt dispenser, main body g1ass,.punched sheet/metal top, 13

holes .078 dia.

Same body, but tops constructed with 7 .078 dia. holes .625 long,y *L/D ratio =8.

plastic top with 75/611 dia., holes Weightof Container Plus Salt N o. Remarks Strt, At `End Net (grams) (grams) Change A 87. 6 87, 9 3 B` 80. 7 8l; 0` -I. 3 Salt caked in bottom. Could not be C 94.3 94.8 5 dispensed. Moisture droplets on Y I 87. 2 87. 5 3.- mslde of glass. .T 87.4 87.8 4 D 174.6- 17416 0 g" 1 g Salt rolled around freely anddis- M 186' 4 ,186 4. 0 pen'sedV easily at end of test. No N 188' 6 188:76 0 moisture on inside of glass. o 187. 1'87. 9' 0 Y K' 98.4 98; 4^ 0 }Salt rolled freely and dispensed L 107. 5 107. 5+ O easily. )L lA 94. 3 94. 4 |'.1 }Salt cakcd Same as A, B, C, I and J.

2 94. 6 94. 7 1 Could not be dispensed. G 83.2 83.4 -I-.2 }Salt veryy lumpy. Clogged onilrst i H 8827l 89.0 +.3 shake. Would not dispense.'

*L-length of holes. D-diameter of holes.

between the container neck and the head.. Also if desired the annular groove 1 may be of a width slightly less than the thickness of thewalls of container neck 4, so that when. head lil isscrewed on the container neck a close lit will result'between the neck and the head. This relationship of groove l and neck. 4 is, of course, possibleonly when the material of Vwhich theheadf` isl constructed is of sufficient resilience.

VAs shown in Figure l,V the dispensing head- B is provided with a'plurality of holes 9- which, as shown in Figure 2,"have a length substantially in, excess of their diameter. Preferably these holes are so tapered that their` upper ends 9a are slightly greater in diameter than their lower 1 ends 9b. Furthermore.v the` length of each: hole is at least four timesgreater than its diameter at. its larger end, whentaperedholes are` used. ByV tapering the holes inthe manner shownany tendencyof the material particles to clog while passing therethrough during a dispensing operation is overcomeasroom is provided, for the particles to move' laterally ofthe axis of' each hole .From` theabove, it may be seen that whereV theA lengthto diameter ratiosof the dispensing Y holes 9 is .in excess of Llsthere isV little Q11 novapor pressure dilerentialv per unit o,f,lengthand,hence negligible moisture vapor transmission therethrough, with the result that the salt remains in a dry,rreadily dispensable condition. Thislength to diameter ratio may, of course, be of any suit.- able value in excess ofV 4, but for practical purposes and maufacturing economy, it is unnecessary to exceed a ratio of 10.

Referring now to Figure 4 wherein I have shown a modified form of my invention, the dispensing head is generally indicated at 2|] and comprises a molded or machined shell 2| having a top 22 and an annular side wall 23 in the lower` portion of which threads 24 are formed. I also form a shoulder 25 on the inside of wall 23 which acts as an abutment that seats on the top of the salt container when the dispensing head is attached thereon as hereinbefore described.

Disposed within wall 23 and preferably integral with top 212 is a downwardly extending partition 26 (Figure 5) which is annular in form and concentric with side wall 23. This partition forms with side wall 23 an annular chamber 21 which, as is better shown in Figure 4, overlies the top edge of the salt container (not shown in this figure) when the dispensing head is attached thereto. The outside diameter of annular partition 26 is, when the head is formed of a semirigid plastic material, preferably slightly in excess of that of the neck of the container so as to tightly engage the container neck when the head is attached thereto.

A suitable number of dispensing holes 28 are formed in partition 26, and these holes may be tapered in the same manner as, and have the same length to diameter ratios, as holes 9 (Figure 2).

Within annular partition 26 and concentric therewith is a downwardly extending tube 29 (Figure 4) which is preferably integral with top 22 and thus provides a centrally disposed dispensing hole 30 which is similar to holes 28. The outer Wall of tube 29 forms with the inner wall of partition 26 an annular chamber 3|.

The form of dispensing head shown in Figures 4 and `5 is particularly desirable Where weight of the head or cost of plastic material is of importance and lends itself more readily to manufacture by injection molding processes. This form of the head otherwise attains the same results as that form shown in Figures 1 and 2.

In Figures 6 and 7, I have shown still another form of my dispensing head which has preferable structural characteristics, particularly where the head is to be formed of a plastic material by an injection molding process. Thus the head, which I have generally indicated at 40, comprises a molded shell 4I having a relatively thin top 42 and an annular side wall 43 carrying interior threads 44 by which the head may be attached to the container. If desired, the inside of side wall 43 may be provided with an abutment or shoulder similar in form and purpose to shoulder 25 (Figure 4) of head 20. Where, however, the container to which head 4l) is to be attached is provided with a finishing ring, such shoulder or abutment may be dispensed with, as the bottom edge of side wall 43 will tightly engage such nishing ring so as to form an air-tight seal therewith where the head is molded of a semirigid plastic material such as, for example, polyethylene.

Disposed within side wall 43, and integral with top 42, are a plurality of downwardly extending tube-like members 45 (see also Figure 7) forming dispensing holes 46 through which the hygroscopic or deliquescent material within the container may be dispensed when the container is shaken. Preferably these holes 46 are tapered with their larger diameters at the top. Holes 46, however, are proportioned similarly to holes 9 6 (Figure 2), i. e. the length of each of holes 46 is about five or more times greater than the mean diameter thereof as to reduce the vapor pressure differential per unit of length to a negligible value.

Top 42 of head 40 is preferably thin enough that it may be readily depressed upon application of pressure thereon. When the top is so depressed, the several tubes 45 move relative to one another in a generally lateral direction, thus to break up and accordingly dislodge any salt or other material that may have been caked therebetween.

The use of a thin resilient head is of added advantage where a slip-t rather than a threaded connection is used between the dispenser top and the body since depressing the top will permit the distortion of the side walls to a point where easy assembly and disassembly may be had.

Thus it may be seen that I have provided a dispenser for hygroscopic materials which attains the several objects set forth hereinabove in a thoroughly practical and eiiicient manner.

I claim:

1. A unitary dispensing head for a container adapted to contain a powdered substance having an aflinity for moisture in the region of that of salt, said head consisting of a body of material having the characteristic of low moisture absorption relative tc the powdered substance within said container, and provided with a plurality of passages extending therethrough, said passage having a length diameter ratio of at least about 4, but not greater than about 10.

2. A dispenser for powdered substances having an affinity for moisture in the region of that of salt including a container for said substance; a unitary head for said container consisting of a body of material having a low moisture absorption characteristic relative to that of the substance being dispensed, and possessing one or more passages extending through said head having a length diameter ratio of at least about 4, but not greater than about 10; and means independent of said passages for holding said head to said container.

3. A unitary dispensing head for a container adapted to contain a powdered substance having an affinity for moisture in the region of that of salt, said head consisting of a body material having the characteristic of low moisture absorption relative to the powdered substance within said container, and being adapted to be connected to said container such that all portions thereof are above the level of the powdered substance when said container is substantially full; and a plurality of passages solely within said head, and

extending therethrough for the passage of said substance from the interior of said container, said passages having a length diameter ratio of at least about 4.

ROBERT W. WARING.

REFERENCES CITED The following references are of record in the file of this patent;

UNITED STATES PATENTS 

